The invention relates to an arrangement for exchanging measuring and/or sampling probes capable of being slipped on to a holding means arranged on the lower end of a vertically movable lance with friction-tight contact, comprising a grab clamping the probe and being movable from an operation position below the lance into a position laterally therebeside.
When carrying out a measuring procedure or taking a sample by immersing a probe into a vessel containing a melt to be observed, for instance a steel works converter, the holding means carrying the probe may be bent, because, for example, the probe is driven against stock not yet melted or pushed against slag parts floating on the molten stock. After retraction of the lance, the probe bent will be in a slanted position deviating from the ideal perpendicular position and thus can no longer be safely seized by the grab.
An additional problem arises when slipping the next probe on to the holding means of the lance by means of the grab, since the probe is held by the grab in a precisely vertical position as rigidly as possible, so as to accommodate the slip-on forces. During slipping on to the holding means of the lance, which, as a rule, is effected by lowering the lance, damage to, or destruction of, the probe by the holding means may occur due to differing positions of the axis of the holding means and of the axis of the probe. For measuring probes, the holding means is designed as a holding rod deeply penetrating into the probe, which near its lower end bar contacts for connecting to the measuring means provided in the probe. When slipping the probe on to the holding rod, damage to the contacts might occur if the probe and the holding rod, are not axially aligned, which may lead to faulty measurements or make measurements impossible.